Suction cleaner



Z X 7/ V m! '30, 1941- c. H. TAYLOR 2,267,364

SUCTION CLEANER Filed July 23, 1938 2 Sheets-Sheet 1 INVENTOR Charles iq vlor ATTORNEY 30, 1941- 3. H. TAYLOR 2,267,764

SUCTION CLEANER Filed July 21:3, 1938 2 Sheets-Sheet 2 N K) R Q j l N \i Q 7 mvsmon L'fiarles H Tqylar ATTORNEY Patented Dec. 30,- 1941 f UNITED STATES PATENTaO FFICE 3,267,764 suc'nox cmamin Charles H. Taylor, Springfield, Mass., assignor to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application July 23, 1938, Serial No. 220,917 In Great Britain February 19, 1938 18 Claims.

This invention relates to improvements in suction cleaners and more particularly to a cleaner so designed as to becapable of supporting its nozzle portion at a substantially constant height above the surface of the floor covering to be cleaned regardless of its quality, texture or'other surface characteristics.

Heretofore, it has been the practice to equip suction cleaners with some form of mechanism or device for adjusting, either manually or automatically, the height of the nozzle for different kinds of floorcovering or for different grades of It is the object of the present invention to perfect the design of a suction cleaner having the inherent ability to maintain itself at the proper nozzle height for different kinds and grades of carpet to be cleaned, this object to be words, it is to be understood that when suction is applied at the nozzle, the carpet is lifted from the floor and held in sealing contact against the suction mouth.

Suction is created within the nozzle by means of a motor-driven fan 3 located within a fan chamber 4 disposed centrally of the casing I and communicating with the nozzle chamber through a suitable inlet passagetherebetween. The motor (not shown) is enclosed within a dome-like cover 5, both being supported upon the flat top surface of thecasing I. Carried at the rear end of the casing is a dirt bag or receptacle 6 having detachable connection with the exhaust outlet from the fan chamber, the upper end of the bag being supported from the handle I, which is pivotally mounted at its lower end in an up-' right supporting bracket 8, suitably anchored at its base by means of screwsor rivets, to the top surface of the casing l adjacent, its rear end. As clearly shown in Figure 1, the handle' mounting is entirely concealed within the rear end,

, portion of the cover 5 which extends to the rear accomplished primarily by a proper distribution of the weight and operating loads, the correct dimensioning of the supporting wheels, and the accurately determinedlocation'for the handle mounting-all without the use or addition of any element or group of elements that might be identified as an adjusting member or part or parts of an adjusting mechanism.

A preferred embodiment of the invention isdisclosed in the accompanying drawings, in which:

Figure 1 is a general view in side elevation of a suction cleaner designed to operate at a su stantially constant nozzle height;

Figure 2 is a fragmentary bottom. plan view of the cleaner showing the mounting for one o the front supporting wheels; and

Figure 3 is a diagram illustrating a graphic method for locating the point of attachment of.

when the cleaner is not in operation. In other end of the casing I and provides a space beyond the motor within which to accommodate the handle supporting bracket. The handle is thusfree to swing in a vertical plane and within a slot in formed in the top rear portion of the motor cover 5.

There is preferably associated with the handle, a torsion spring Ia carried on the pivot pin to and acting to exert a constant pressure upon the handle in a direction to oppose its free movement in a downward direction when released by the operator. Also, a handle retaining or latching means may be included as part of the handle mounting to retain the handle in an upright'or storage position, but this latter device need not be included in the present disclosure as it is incidental to the novel subject matter.

As already suggested, the casing is supported upon wheels, namely, a pair of front wheels '9, 9 and a pair of rear wheels, III, III. The rear wheels comprise a rather common type of caster mounting including a bracket I I suitably fixed to r the underside of the cleaner casing and forming a support for a shaft I2, on the opposite ends of which are journalled the two rearwheels III,

, III. For convenience it may be assumed that the rear wheels are of standard size-that is, approximately 1% inches in diameter and say of an inch inwldth measuredcrosswise of their tread surfaces.

The front wheels 9, 9 are located immediately 5 behind the nozzle chamber and well outwardly toward the ends thereof, it being understood that there would be a wheel 9 corresponding to that shown in Figure 2 on .theopposite side of the cleaner casing, had it been'considered necessary to complete the bottom view. With'the exception of the size and dimensions of the front ortant cl presently out wheels mounted is not i is more or less cone .,n and need not desc 1 e former are approllrmateiy twice the size latter, both in diameter and treadsuzface, so that assuming the rear wheels to be of standard size, that is, from one end and 'three-eigthe (1%) inches to one one half (1 inches in diameter and from oneauarter to three-eighths inch tread width, the dimensions of the front wheels would be approximately three (3) inches in diameter and from three-quarters to one (1) inch in width of tread surface. I,

Now, it is obvious that the greater the diamstar and the wider the tread surfaces of wheels,

the greater will be their ability to support the load "of the cleaner upon the carpet with ,less penetration or sinking into the carpet pile. Again, considering two pairs of wheels, one supporting the front and the other the rear end of the cleaner body, it is possible to proportion the wheels so as to establish a so-called penetration ratio therebetweeu, that is a relationship between the respective abilities of the front and rear wheels to resist pile penetration so that for all types and grades of carpet and rugs ordinarily encountered in homes, a condition of substantially uniform nozzle height will be obtained. And in this-connection, the term substantially uniform nozzle height may be defined as a condition approaching uniformity of nozzle height regardless of the kind, texture or characteristics of the particular carpet to be cleaned, but yet Q closely woven and shorter piled carpet. In other T words, it is to be understood that the term constant nozzle height has reference also to that best suited to the particular carpet to be cleaned, rather than to the maintenance of a fixed nozzle height irrespective of carpet characteristics.

With this explanation in mind, it follows therefore that the desired dimensional relationship between the front and rear wheels must be determined for each type or model of cleaner and based upon the weight, suction, load distribution and other factors to be presently mentioned.

Generally speaking, the ability of a wheel to resist penetration or sinking into the pile of a carpet is a function of the area of its tread surface in contact with the carpet and this area is dependent primarily upon the width of the tread surface and secondarily upon the wheel diameter,

with the tread width the more important factor.

- are again, the particular manner in which the acetates Again, with the cleaner supported upon sets of front and rear wheels and the suction applied at the nozzle, it follows that the greater resistance to pile penetration is to he demanded of the 5 front wheels and hence their size which can be controlled either by their tread diameter, or both) would imxariably be greater than of the rear wheels. But no nits relation e dimensions heat and rear cleane although-it eectual depth 1 under varye and this ratio of penetration is ase practically the same for all grades s worn charts such as mentioned above, correct sizes front and rear wheels can be selected to give predetermined penetration ratio, say 1 This means that, for each unit of depth the front wheels penetrate the carpet tit) nap, the rear wheels will sink or penetrate to a depth of 1.75 units, from which it follows that, upon placing a cleaner in operation upon a carpet, the wheels will sinlr into the carpet pile in the ratio of l to 1.75 with the rear wheels sinking to the greater depth. As a consequence of with the transverse center line of the suction mouth, or it may be found to lie somewhere ahead of the nozzle. In other words, the cleaner does not sink equally on all wheels, but settles back, after a fashion, on its rear wheels.

But it should be noted in analyzing the penetration of the front and rear wheels into the carpet nap that, unless the theoretical axis about which the cleaner body tilts actually coincides with the transverse center line of the suction mouth, it is not quite correct to assume that the plane of the nozzle mouth will remain at the same height above the carpet, with only its plane tilted slightly to the horizontal; for the fact is, with the penetration of the front wheels into the carpet pile, the nozzle will be lowered altration by wheels having a given penetration ratio, namely, adefinite tilting of the cleaner about the front wheels as a fulcrum. In practice, this secondary effect is coupled with the bodily rocking movement of the cleaner about its imaginary turning axis, lying either within or without the body of the cleaner, and introduces a compensating effect in the nature of an added or increased elevation or tilting of'the nozzle upwardly and in an amount substantially equal to the distance the nozzle is lowered due to the penetration of the front wheels, and which incidentally, cannot be avoided in practice. In other words, the result of this secondary tilting movement of the cleaner about the front wheels is to compensate for the depression of the nozzle due to the un- 1 one that is correct for effectively cleaning that particular carpet; be itslightly higher or lower than the height of the plane of the suction mouth above the plane established by the contact points of the wheels.

As it is desired that the nozzle height shall not vary appreciably relative to the surface covering, theoretically front wheels of sufficient surface-contacting area would accomplish this result but all practical wheels will. sink into the covering a certain amount, that amount depending upon the characteristics of the covering. To compensate, for this penetration of the front wheels, which will of course tend to lower the nozzle, it is necessary that the rear wheels penetrate or sink ,to a still greater depth in the covering in order that the machine can be tilted about the axis of the front wheels to effect a raising of the nozzle to a degree sufllcient to offset the aforementioned lowering thereof caused by the front wheel penetration. It is obvious that theoretically, if the center line of the nozzle is to remain at a fixed position and the front and rear wheels are positioned at different distances from the nozzle and upon one side thereof, that the penetration ratio of the front and rear wheels should vary directly as the distances separating their axes from the nozzle center line. This would give optimum performance theoretically.

And in connection with the determination of correct wheel sizes, it may be observed that when rear wheels of standard dimensions (say, 1%

inches in diameter and inch tread width) are used, it is only necessary to dimension the front wheels so that they will support the forward portion of the cleaner without appreciable penetration of the carpet nap. In short, it may be quite practical todisregard entirely the penetration ratio as between front and rear wheels and simply assume that the rear wheels will sink to a uniform depth regardless of the kind or charactor of the carpet on which the cleaner is operated. In fact, it may be possible, although perhaps not altogether desirable, to use a special form of rear wheels having their tread surfaces beveled to a V-shaped contour in order to insure a maximum penetration to the very foundation ness of its nap. Such an arrangement would always insure a firm foundation for the rear wheels and a nozzle height that would be dependent wholly upon the ability of the front'wheels to support their load with minimum penetration of the carpet nap. although a possible undesirable feature of this arrangement would be the i As a consequence, the propelling force is continually changing in value, angle and direction.

For example, during the forward stroke of the cleaner, the force is exerted downwardly along the handle and a portion of this force (the hori zontal component) acts to overcome the resistof the carpet regardless of the texture or thickance to the movement of the cleaner over the the force of gravity and thus depress the rear end of the cleaner casing. And finally, there is the stability of the cleaner to be taken into consideration, both in its static condition and in operation. The handle should not be mounted so 'far rearwardly as'to create a tendency for the cleaner body to tilt backwardly on its rear wheels when the handle is in any position. other than its upright storage position. And more important, the'handle pivot should not be so located that when the cleaner reaches the end of the forward stroke and its direction of movement reversed, there will be a definite tendency for the front end of the cleaner to be lifted from the carpet surface. This tendency is more pronounced whena sudden jerking movement occurs at the commencement of the return stroke, in which case it is preferred that the rear end of the cleaner be lifted rather than the front or nozzle end and for the obvious reason that the lifting of the front end of the cleaner means the breaking of the seal between the nozzle and the carpet surface and a consequent temporary loss of cleaning effectiveness.

As a consequence, therefore, it is quite as important to have the handle properly located as it is tohave the wheels of the proper dimensions.

In other words, in order to obtain most effectively the condition of substantially constant nozzle height in any cleaner it will be found desirable to give attention to both the relationship of wheel dimensions and to the handle pivot location. Attention to either factor, however, will give improved nozzle adjustment and position.

Generally speaking, the handle should be mounted at a point such that forces exerted through the handle in the movement of the 'cleaner over the carpet surface will be least noticeable in the performance of the cleaner and more especially, will interfere least with the distribution of the operating load between the front and rear wheels and the travel of the front wheels over the carpet will be accompanied by a minimum as wellas a uniform depth of penetration of the pile. In other words, the handle should be so mounted that the force exerted through the handle will be rendered as ineffective as possible under all conditions of operation.

Thus, with the desired conditions tube at tained in mind, it is possible to determine the location of the pivot point of the handle within limits which can be fairly well defined with accuracy both longitudinally and vertically so that with the handle pivot, once located, the forces exerted through the handle will least disturb the .uniform nozzle height conditions which would Thus, for any given cleaner, the location of the pivot point of the handle can be accurately determined by a method which would ordinarily be performed on the drawing board and preferably after a model has been constructed for test purposes. This method will now be briefly described as follows: First, having laid out the cleaner on paper to full scale, asshown in Figure 3, its true center of mass, as determined from the actual model, is found to lie approximately midway between the front and rear wheels. Hence, the dead weight or the static load would be represented graphically by a vertical line L passing through the center of mass. But since the cleaner operates under the force of suction acting to draw the nozzle downwardly, this force may be treated as an additional vertical load S applied at the center of the nozzle and, with this load added to the static load the resultant of these combined loads may be represented by a vertical line L2 located slightly forward of the static load line L1 and passing through an imaginary transverse axis about which the various forces acting upon the cleaner in operation would be in equilibrium, but excluding the forces exerted through the handle.

Now, having located the line L which represents graphically the actual and measured resultant of the combined static load and the suction load, the next step is to locate the resultant of the forces which combine to resist the movement of the cleaner in a forward and rearward direction. These forces consist of the wheel fricassayed the handle in maneuvering the cleaner over the carpet surface would be exerted. To do this, it is first assumed that the mean angle of inclination of the handle is 45 although actually the inclination of the handle would vary somewhere between 55 and 35 to the horizontal. However, at the outset it is assumed that the handle is fixed to the body of the cleaner at an angle of 45, and further that this imaginary and theotion, resistance offered by the carpet nap, friction of contact between the nozzle and the carpet, the suction seal between the nozzle and the carpet, and finally, the contact between the rotative agitator and the carpet as it is held against the suction mouth. Incidentally, the direction of rotation of the agitator is such as to aid the movement of the cleaner in a forward direction I and to oppose its movement in a backward direction.

Now, the resultant of these forces opposing the forward movement of the cleaner may be represented as acting in a rearward direction and along a horizontal line R spaced 9. short distance-above the center ofthe front wheel axis. it being understood that the location as well as the value of this resultant has previously been measured and determined by test. Similarly, the resultant of all forces opposing the movement of the cleaner in a rearward direction is represented by a horizontal line R which is located approximately half-way between the floor level and the front wheel axis, it being understood that it is the reversal of direction of the forces exerted through the handle during the forward and backward strokes of the cleaner that is responsible for the vertical spacing as well as in the difference inthe value of these resultants. And further, in connection with the resultants R and B, it should be stated that they represent the maximum condition which would be encountered in actual practice and determined by test of the model on the several kinds and grades of carpet most generally found in the average home. Thus, the resultant R represents mum resistance to forward movement of a. cleaner under the extreme conditions and R? represents the conditions of least resistance to movement of the cleaner in a rearward direction.

Now, the next step is to locate on the diagram 1; band or strip within which would lie 9. theoretic line along which the forces applied through retic line of force will pass through the body of the cleaner and intersect the floor line rearwardiy of the point of contact of the front wheels in order that the turning moment of forces exerted along this imaginary line will not create a tendency for the cleaner to tilt forwardly during its forward movement or to tilt backwardly during the return stroke and resulting, as pointed out earlier in this discussion, in undue wear on the carpet on the one hand and the loss of cleaning efi'ectiveness on the other. In other words, the forces exerted through the handle should be so applied as to produce a. effect upon the maneuverability of the cleaner by bringing about a condition such that the front supporting wheels are relieved so far as possible of all variations in operating load, since after all the front wheels are the members which gauge the height of the nozzle.

Thus, it follows that the ultimate purpose of the present cleaner design is to approach as closely as practically possible a condition in which the height of the nozzle can be maintained substantially uniform by minimizing the undesirable efiects produced by having to exert forces through a handle in order to maneuver the cleaner.

Consequently, the first step in locating the imaginary band or zone is to draw a line F through the point of intersection of the vertical resultant L and the horizontal resultant R at an angle of e5 and another parallel line F through the intersection of the same vertical resultant L and the second horizontal resultant R And so, having located this imaginary zone on the diagram (Figure 3) by theinclined parallel lines F1 and F2, it is assumed that the handle force must be exerted along a line falling withinv this zone if a proper nozzle height is to be maintained during both forward and rearward strokes. This can be demonstrated from the diarespectively, would be zero in each case, providing the cleaner ismoving at a uniform speed in both directions and assuming further that the propelling force s applied wholly in a horizontal direction. And so, if the lines F1 and F2 are drawn through these points of intersection at the mean handle angle of 45 degrees, it follows that as long as the force exerted through the handle follows a line passing between these lines, the tendency for the cleaner to tilt backwardly or forwardly with each reversal of direction of movement will be reduced to a minimum, thus leaving the front wheels free to support the nozzle at the proper height with respect to the carpet surface.

and rear wheels in the same proportion as are the static and suction loads. In other words, the forces exerted through the handle are distributed between the front and rear wheels in such a manner as to ovoid varying the proportion of the load thereon under operating conditions.

From the foregoing explanation, it can be now determined that the handle is to be attached to the cleaner somewhere within this inclined band" or strip and the next step is to locate the point of connection of the handle lengthwise of this band. The vertical location 'of the point of attachment of the handle is not difiicult when it is pointed out that the handle swings in a certain arc and that by locating the pivot point of the handle over the rear wheels, the variation in the load carried by the front wheels by reason 'of the varying angular application of the handle force is reduced to a minimum.

Thus, it can be concluded that the correct point for locating the point of pivotal attachment of the handle to the cleaner body should also be directly above the rear ,wheels, that is, in the vertical line passing through the axis of the rear wheels. been found that the theoretic line of force exerted through the handle should fall within the band or zone defined by the inclined lines F and F it would be correct to conclude that the pivot point of the handle should be located within the band and on the vertical line V passing through the rear wheel axis.

But there are certain variable factors to be taken into consideration, which have previously been mentioned. For example, the weight of the dirt bag and its contents will vary depending on the length of time the cleaner has been operated though for the purposes of the calculations just outlined, it is so-considered, since in practice the suction will vary somewhat with the type of carpet being cleaned. Therefore, on account of these and other variable factors, it may be desirable for the best results, to shift the point of attachment of the handle a short distance forwardly or perhaps rearwardly of the vertical line passing through the axis of the rear wheels. Hence, to make allowance for a limited horizontal shifting of the final pivot point, it is preferable to extend the range of possible handle pivot positions to an area'A described by the intersection of the inclined band or strip already identifled and a relatively narrow vertical band, the limits of which lie 9. short distance on either side of the vertical line V passing through the axis of the rear wheels. This area,

'as indicated by the shading in Figure 3, has the general form of a vertically elongated parallelo gram and, having located this area, it may bestated that the pivot point of the handle should be located within this relatively restricted area to insure a substantially uniform condition of nozzle height throughout the entire range of And since it has already tical alignment with the axis of the rear wheels. In any case, having located the pivot point according to the method herein prescribed, it can be definitely assured that the cleaner will 5 operate to the best advantage for the particular carpet being cleaned, riding over the surface with a maximum degree of smoothness, equality of load distribution and at a uniform nozzle height best suited for the existing conditions. And finally, a cleaner designed in accordance with the present disclosure to be self-adjusting as to nozzle height to the particular carpet or rug being cleaned, has definite merit in that it does not require the use of any adjusting mechanism or the addition of a single auxiliary part in order to obtain the desired result. In fact, the advantageous self-adjusting nozzle height feature may be said to be built into the cleaner and hence inherent in its design, rather than by the incorporation into or the addition to the cleaner structure of some adjusting mechanism intended to respond to different types and kinds of carpet and, by acting upon adjustable supporting members, to raise or lower the nozzle to meet 5 different carpet conditions.

Having set forth a full and complete disclosure of the invention, I claim:

1. A suction cleaner designed to insure substantially uniform nozzle height regardless of the character of the carpet being cleaned, comprising a body having a nozzle at its forward end and front and rear supporting wheels, said front wheels having a tread surface area substantially greater than that of the rear wheels and capable of supporting the forward portion of the cleaner with limited penetration of the surface of the floor covering being cleaned, and a handle attached to said body at a point located above the rear wheelsand along the line of force exerted 40 through said handle in its mean position of inclination of approximately during cleaner operation which line passes between the intersections of the resultant of the suction and static 45 lines of direction of the resultants of forces opposing forward and rearward movement, respectively. of the cleaner in operation.

2. A suction cleaner designed to insure substantially uniform nozzle height regardless of the character of the carpet being cleaned, comprising a body having a nozzle at its forwardend and front and rear supporting wheels, said front wheels having a tread surface area substantially greater than that of the rear wheels and capable of supporting their portion of the operating load with only a relatively limited penetration into the surface of the floor covering, and a handle mounted on said body at a point located substantially directly above the rear wheels and on a line representing the direction of forces exerted through said handle in its mean operating tally spaced lines of direction of the static load,

and the resultant of the static load and suction load, respectively, with the direction line of the resultant of the forces opposing the forward loads of the cleaner with the vertically spaced surface area great enough to enable said fronton said body and at a point to be located within an area defined by the intersection of a band inclined to the horizontal at a mean operating handle angle of substantially 45 degrees and bounded by imaginary parallel lines passing through points markingth intersection of a vertical line representing the resultant of the combined static and suction loads with spaced front and rear wheels at substantially the same point as the direction line of the downwardly directed operating loads.

4. A suction cleaner comprising a body hav ing a nozzle and front and rear supporting wheels joumalled on fixed bearings mounted on the un- 1 derside of said body, the front wheels being offset from said nozzle and having tread surfaces of an area capable of supporting the operating load with relatively limited penetration of the carpet nap and the said rear wheels having treadsurfaces of a width capable of supporting the load with correspondingly greater depth of penetration, the ratio between the areas of the tread surfaces of said front and rear wheels being pre-- determined to permit the tilting of the cleaner body about said front wheels and in a direction and amount calculated to compensate for the depth of penetration of said front wheels: into the carpet and thus maintain said nozzle at a substantially uniform height regardless of the character or texture of the carpet, and a handle attached to said body at a point substantially directly above the axis of the rear wheels, as described, and which lies on an imaginary line inclined at approximately 45 and which intersects the plane of a supporting surface immediately rearward of said front wheels.

5. A suction cleaner comprising a 'body having a nozzle and front and rear supporting wheels Journalled on fixed bearings mounted on the underside of said body, the front wheels being offset from said nozzle and having tread surfaces of an area capable of supporting the operating load with relatively limited penetration of the carpet nap and the said rear wheels having tread surfaces of a width capable of supporting the load with correspondingly greater depth of penetration, the ratio between the areas of the tread surfaces of said front and rear wheels being predetermined to permit the tiltingof the cleaner body about said front wheels and in a direction and amount calculated to compensate for the depth of penetration of said front wheels into the carpet and thus maintain said nozzle at a horizontal lines representing the resultants of the resistance forces acting during the forward and backward strokes respectively of the cleaner,

substantially uniform height regardless of the a character or texture of the carpet, and a handle pivotally mounted on said body at a point to 'of the vertical loads and the lines of direction of the resultants of the horizontal forces opposing the cleaner movement during the forward movement and the backward movement, respectively, of the cleaner.

6. A suction cleaner designed to insure a substantially uniform nozzle height regardless of the character of the carpet being cleaned, comprising a body having a nozzle .at' its forward end, front and rear supporting wheels, said front wheels having relatively large diameters and wide tread surfaces calculated to support the forward endgof the cleaner under its normal operating load with a minimum 'of penetration of the carpet nap, and a handle pivotally mounted and a relatively narrow vertical band including the axis of the rear wheels.

- 7. A suction cleaner designed to insure substantially the correct nozzle height for the particular fioor covering being cleaned, comprising a body having a nozzle at its forward end and front and rear supporting wheels fixed in positionrelative to said body in cleaner operation, the tread surface areas of said front wheels being great.

enough to carry the operating loads with but relatively limited sinking of said wheels into the surface of the floor covering, the resultant of the operating loads being positioned rearwardly of and immediately adjacent said front wheels-and a handle mounted on said body at a point located above the rear wheels and in the line of the forces exerted through the handle in its mean rearwardly inclined operating position of approx! imately 45 degrees and intersecting the lines of direction of the resultants of the, horizontal forces opposing the movement of said body during cleaner operation in either direction at points positioned immediately rearwardly of the axis of the front wheels.

8. A suction cleaner designed to insure substantially the correct nozzle height for the particular floor covering being cleaned, comprising a body having a nozzle at its forward end and front and rear supporting wheels fixed in position relative to said body in cleaner operation,'the tread surface areas of said front wheels being sufliciently great to carry the normal operating loads with but relatively limited sinking of said wheels into the surface of the floor covering, the resultant of the operating loads being positioned rearwardly of and immediately adjacent said front wheels, and a handle pivotally mounted on said body above the rear wheels and in a line passing through the body at the mean handle angle of approximately 45 degrees and intersecting the imaginary direction line of the resultant ,of the horizontal forces opposing the movement of the cleaner inoperation in a forward direction at a point immediately rearwardly of the sitioned rearwardly of the center of mass and having a lesser surface-contacting area than said front wheels, the surface-contacting areas of said front and rear wheels bearing a ratio such that said rear wheels sink into a supporting covering sufficiently to tilt said body about the front wheels to raise said nozzle in order to compensate for the lowering of said nozzle effected by the sink of said front wheels. V 10. The structure defined by the preceding claim characterized in that a pivoted handle is connected to said body at a point such that with said handle in a 45 position the axial handle propelling force is proportioned between said front and rear wheels in the same proportion as the other vertical operating loads.

11. The structure defined by the second preceding claim characterized in that a pivoted handie is connected to said body above said rear wheels and at a height such that a line at an angle of 45 through the pivotal axis intersects the supporting surface in the proximity of and rearwardly of the contact of the front wheels therewith.

12. In a suction cleaner, a body including a nozzle, front and rear supporting wheels rotatably mounted on axes fixedly carried by said'.

'wheels being less than that of the'front wheels and in a ratio to produce a tilting about the front wheels by their greater sink into a-covering which tilting raises the nozzle to compensate for the lowering thereof effected by the sink of said front wheels, and a handl pivoted on said body at a point located substantially directly above the rear wheels and on a line representing eluding a nozzle andfront and rear supporting means fixedly connected to said body during cleaner operation, said front supporting means being positioned rearward of and adjacent said nozzle and having a surface-contacting area capable of supporting the operating load by penetrating only slightly the pile of a surface cover.- ing undergoing cleaning, and the rearsupporting means having a lesser surface-contacting area and adapted to penetrate to a greaterextent the pile of said surface covering, the ratio between the surface-contacting areas of said front and rear supporting means being such that the penetration of the. rear supporting means into a supporting surface is sufficiently. greater than the penetration of the front supporting means as to effect a tilting of the cleaner body about said front supporting means for the purpose of compensating for the lowering of the nozzle effected by the penetration of the front supporting means.

and second spaced supporting means fixedly conthe direction of forces exerted through said handle in its mean operating position of which line passes between points determined by the intersection of the horizontally spaced lines of direction of the static load, and the resultant of the static load and suction load, respectively, with the direction line of the resultant of the forces opposing the forward movement of the cleaner in operation.

13. A, suction cleaner comprising a body having a nozzle at its forward end and supporting wheels joumalled on fixed bearings adjacent its front and rear ends, said front wheels having a combined tread surface area greater than the rear wheel tread surface, the ratio of said surface areas in contact with the carpet being substantially proportional to the relative resistance of said wheels to depression into the pile of the carpet being cleaned and thereby maintaining said nozzle at a substantially uniform height regardless of the kind and character of the carpet being cleaned.

14. A suction cleaner comprising 'a body having a nozzle and front and rear supporting wheels journalled on fixed bearings mounted on nected to said body during cleaner operation and.

having surface-contacting areas, said first supporting means being positioned at one side of said surface-contacting means and having a surfacecontacting area capable of supporting the operating load carried thereby withonly slight penetration of the pile of a supporting covering undergoing cleaning, said second supporting means being positioned upon the same side of said surface-contacting means as said first supporting means but at a greater distance therefrom, said second supporting means having a lesser surfacecontacting area and adapted to support the operating load carried thereby with greater penetration of the: pile of the surface covering undergoing cleaning, the ratio between the surfacecontacting areas of said first and second supporting means being such that the penetration of the second supporting means into a supporting surface is sufiiciently greater than the penetration of the first supporting means as to effect a tilting of the cleaner body about said first supporting means for the purpose of compensating for the lowering of the surface-contacting means effected by the penetration of the first support face covering undergoing cleaning, said result ing the load with correspondingly greater depth of penetration, the ratio between the areas of the tread surfaces of said front and rear wheels being predetermined to permit the tilting of the cleaner body about said front wheels and in a direction and amount calculated to compensate for the depth of penetration of said front wheels into the carpet and thus maintain said nozzle at a substantially uniform height regardless of th character or texture of the carpet. 15. A suction cleaner comprising a body inbeing effected by providing front supporting means having an area which supports their part of the operating load with slight surface covering-penetration and by providing rear supporting means of lesser-area adapted to penetrate a surface covering to a greater extent under their part of the operating load, and by positioning the centers of said supporting means at'distances from the center line of said nozzle which distances are in substantially the same ratio as the distances of penetration of said supporting means in a surface covering undergoing cleaning under the operating loads carried thereby.

CHARLES H. TAYLOR, 

